Radio broadcast distributing system



' March 19, 1929. E. E. CLEMENT 1,706,379

RADIO BROADCAST DISTRIBUTING SYSTEM Filed Nov. 25, '192.5 4 sheets-sheet 1 Qwk um o.. k WQQ mm QW un N NN @N March 19, 1929. E. E. CLEMENT 1,706,379

RADIO BROADCAST DISTRIBUTING SYSTEM Filed Nov. 25, 1925 4 Sheets-Sheet 2 Ma'rcb 19, 192.9.v f E. E. CLEMENT 1,706,379

ARADIO BROADCAST DISTRIBUTING SYS-TEM File-d Nov. 25,- 1925 4 sheets-551mml 5 WSH March 19, 1929.V E. E. CLEMENT i RADIO BROADCAST DISTRIBUTING SYSTEM Filed Nov. 25, 19.5.5

4 Sheets-Sheet 4 .Patented Maf-519, i929.

l A-Myinvention relates vto the art'of broad- `rland has for its object. to produce a system i y Actif-transmission Which shall be eiicient, Secret, and shall be non-interfering With re- 'i .eratingon'Waveba'ndsadjacent toor even y"fo,verlappii'igin frequency the Wave band or bandsA4 employed herein. The yfull` system T I'Oyin which this invention j is yparticularly "adaptedf vto Abe used is ,that disclosed No..746,357, filed October 28, 192e, patented. k.July 5,5192?, No.v 1,635,153. In said applicationlI-havedescribed a system of broad- ,.l-cast distribution in which the ultimate'relceiving .stations are divided into groups, 'fjeach' group served by a local or regional ybroadcastingstation Which may both relay Vafnd originate programs. These regional Vstations v (c'alledfG stations) are in. turn x grouped accordingto districts or divisions, ff'which tare rserved by kdistrict or divisional r"r-vvhichjr may also both relay vand originate i f lated toa master station (called A station).y The severa-l stages ot distributing or relay ,stationshave interconnection by vradio chan- "Delsland Wire trunk lines, and the regional orjCstationsma-y be connected with their several groups of receivers or subscribers by Vqvvire lines, such. as telephoney lines, v'which Aenable supervision, testing, metering, and the rililretolbe.performed locally.y Vlith a sys- -jtem Vorganized as' thus described, great Hein-f Ebility'is possible whereby average eiiciency #oftiansmissionithroughout the entire system bemaintained at'fallytimes and under allfconditions.;l` and the ingathering and dis.- ti'ibution"o'fmaterial may be arranged so as j'to enableglocal subscribers with simple in vi'unieiits yto receivefioin any part of the stein; and inakeselection' of all items from plurality of programs. 'A feature. ofthis gathering and distribution is the moduitin.oaudiosignals at or near 4thelpoint oi'igimupon carrier fwaves of a frequency suitable Vfor transmission f over Wire circuits,

v tvaves interchangeablyover Wire circuits or bvil'secondary'modulation upon a high fre- -'qiiency fcarrierj Wave withV subsequent radia# tion?thereof.` y j .In lthey presentlcase, I attain my objects,

l f 'f viq-casting and-particularly radio broadcasting,l

s'pect'gto other systems Vlsimultaneously opf-Y inlniy priorcopending application, SerialV Vbroadcasting.^ .stations` (called B stations),-

programs.v All these relay stations-'are re t EDWARD CLEMENT, or i'ivAsHINc-froii,l DISTRICT or ooLUii/LBIA, Assieivon To ED- WARD E. ooLLADAxoF WAsHIiiG'rolv,l DIsTRio'r 'or ooLU'ii/IBIA; v

' RADIO BROADCAST DISTRIBUTING sYsTiiiirfr Application led November 25, 1925. Serial N'o.:v71,4u57. l

-iand attheV same time render'th'e invention applicable to. the general system above described, as follows: Audio rejquency signals .are modulated 'upon a suitable carrier Wave lo1 -superaudio frequency; the resultant-composition current minusv current variationsoi' the said intermediatefrequency are `then modulated-upon a primary radio frequency carrier current and are'radiated nthesame as alpiimary carrier Wave. VThis primary 'carrier Wave is receivedl at a distantstatioii,

deinodulated to detectrof the intermediate frequency composition current,andtheorig- `inal intermediate frequency `carrier current .istiansmitted separately and-by'means of a separate mediumto the. receiving-station vfor recomposition with. said detected` com- POsition current tofreproduce. vacarriercui1- rent of the original"intermediate frequency modulatedl with the audiosignal .Wave ;j andA lcurrent is then demodulatedby this vcarrier .detecting off the audio signal Waves there from. Y .l :1 i .My invention isfillus'trated. inthe accompanying drawings, 'in which* Fig. lis a diagram ,of asystem embodying the invention, using-- conventionalized .symbolsivith no detail.v f i Fig..j' 2is a diagraml showingthe detail of circuits that may feemployed in themaniier indicated in Fig. 1. l

- Fig. 3 is adiagram similar to Fig. 2, Withsome parts conventionalized/as in y1, showing isecondaryginodulation 1 upon :a cai'- i'ier Wave.producedfasaf harmonicof the carrier wave originally 'A used in `primary u modulation; the original carrier .Wave being,

lalso` shown as transmitted toi thereceiving l station, With vmeans for deriving the sameharmonic therefrom for use. Vin.recomposing the original modulated carrier Lform. j

rFig 4 shows a diagram oi still another modified arrangement, in-Whi'ch a balanced \rimary modulator employed with .the Colliitts-Heising circuit for secondary modu- -lation;'the receiver ingthisligure being also i. modified; by.: the l elimination of they saparate 100AIV composition circuit shownin'- Figs.- l, 2 and Ifbetvveen the first andV second detectors. U. and.V the vtransmissionf of 'these modulated `to the receiver circuitofFig.. 4. f

Referring to Fig. :1, lf'represent's an audio frequency modulator .'sucli' las fa microphone circuit, Working into a super-audio fre-V lll 0 an amplifier Y22 to the line 25 extending;l 4o

- subscribers station comprises'a receiving'-s whicli band/is the result .of the modulation `.of .the base f1equency'by1the audio frequency signalv Waves.. VThe Vreception at the subscribers station is the same asnthat described for Fig. V2. f f

` vIn the, arrangement ,of Fig. lpthe audio frequency signal currents generated by the microphone M and battery MB are component as acarrier, Whichband i-siniodulated onto a primary radio frequency carrier through a Helsing oscillator and modulator unit lllf. and the resulting double modulated primary Wave radiated from The double. tube modulator 2 is of the type disclosed in the patent Vto Carson, No.

175543,307, patented J une I 15, V1920, ,Whilev the oscillator andmodulator unit isfthe' usualy Heising typeL in which O is thefoscillator though not shown, it Willi he understood'that:

suitable amplifiers may be used both 'be fore and after the oscillator-modulator unit, as Well as a filter vcircuit` or circuits between the output of the modulator 2 andthe input of the modulator tube M() or ,an amplifier preceding it. The arrangement forsupply-V ing the intermediate frequency carrier current to the subscriber 1sv substantially "the same as that of Figs; l to'ff,` and comprises the `coupler 2l connected to transfer current from theY circuit ofy the'source t through to a, subscribei"s station.v Y This subscribers linetas in the preceding arrangements','may be a special line forjthe present use only or. may beVY any line alsoused for ,other seryice such as a commercial power supply line vorcv a telephone line as here shoWnf-byfway ofl example. rlhe radio receiving set at the ant-enna 26T coupledlto the" input circuitofv a detector V28'- arranged vto receive and vce' d emodulateV theV` double modulated primary ware'radiated from the antenna 1S toldetectA` out the 'intermediate frequency baudgandtransfer the saine, after `re-coiuposition' `With the original intermediate vrwavc,j to' the 1nput circuit of a secondl detector36V arranged to demod'ulate'the composed or synthesized jwave to detect outthe audio signal Wave anddeliver the vSame tothe receiyer". Recom-V vposition is here effected through, a composition transformer 82 corresponding` 1n func- Vtion. to the composition. circuitf32 of Figs. Y1 V and 2 and comprising the three Windingsl 3 3 and 35 having a 'common magnetic field and connected respectively-.in the output cir- .cuitof the first'sdetector 287 acrossrthe line the antenna 18 25 through extensionr, and in the `input circuit of thessecond detector 36,'. Vl`hus,xthe

band detected from theY prin'iarycarrier re-Y 1a link circuit-l32't0 be coupled 'through transform ers 131,' 133 and Y 135,1 respectiyely,

vtothe outpu-tof the Afirst detector 28",to the Vline through extension [34 and tothe input ofthe second:detectorVV 36 It rshould be understood-thaty the circuits and parts thereof shown herein,` are Lfor definition only and not forpurposesfof limitation. Thus, Vin :pi-"actice5I especially where secrecy is desired,` properliilters will be employed ato or after 1() Fig. 1 to pass only one side band. l Many otherrefinementsy Y Y Y u 'and modifications will occurvto'those skilled tube and MO the modulator tube,'the oscillator circuit being adjusted to produce oscilla-v tOns of Vthe desired, radio frequency.'v Alin theart after readingthiszspecicatiom oinodyne duplexl 'receiving ,sets `ofthe Tso-V,V

called @arson type may be employed, andthe ter for betterusefinthe system/of 'my prior ycopendingA application7 lSerial No.` 7465357, hereinbefore referred to. 1 Inthe" specificy form' described, only unmodulatedsuperaudiofl Y Vcurrentis transmitted over Wire circuits'.V4 The Vinoduilatingtransmitterp14-2 vof 1 muy f be? replaced by van equivalent relay transmit-v ulated'-currentflioweyenl donot bari the ...use of selective n, or filtering apparatus to take out somerof,i the frequencies inthe rnlodi les Y ulatedv band, and transmitv the Vsame*vr over` radiation, lfor purposes ofusecrecy.

The use ofa harmonic generator' or'what I 4 have called herein a harmonic producer@ vthe WireY While transmitting the balance'by lll() f through which thefrequency of the radiated I vWave -is definitely related tothe frequency?. of t-he initially modulat'edfwave,v leads'to'a l' line of development Whichis-n'ot fullyidelyscribed herein', as'itldoes not` relateto the Y jsamespecihc invention. VI-Iofweveigjt should, be stated that the production of harmonicsv in the broader senseherein indicated, makes itp'ossible to inodulateyor rathertoproduce Waves of radio yfrequency" and 'bearing vsignal l modulations, bycausing the original low frel quenrcy signal waves toV produceharmonics,V f "i kstepping upfto the v'desired ,order of fre- .Y fluency, which starting. from fthe audio fre? quencies.mightY beV to Vithef'sixth or eighth the secondary circuit V14 are'fn'ot harmonics V.f ictaye for radio frequencies. "Generieally, v kthisu'dea isthe s'ame'as vlnft'he present case,

altliought vinA this case"l thel v moduletions 1in" circuit Yl, but they contain harmonics of frequencies 'which are found in the composition of the audio Waves With the carrier frequency ofthe generator 4. Broadly speak-r ing,the secondary modulations may therefor be said to be in harmonic relation to the. loW frequency modulations, and obviously the stepping up in such harmonic Y. relation might- Wellv begin with the audio.

frequencies themselves. In such case, selection Vof particular partsl of -the spectrum would have to be made in order that a given Y number of constituent frequencies represent- .f ing harmonics of the original audio Waves may besbrought together in the receiving cirv cuits for recomposition and detection. Theoretically, the audio portion of the spectrum l may contain an infinite number of frequen` I cies; but'avvery limitednumber maybe selected, Without sacrificing l for stepping up, radiation, and recomposition.

pitch or quality What i claim is; l. The method of radio broadcast trans- Ymissionwhich consists in modulating audio '-y signal Waves onto a carrier current of superaudio intermediate frequency, modulating the resultant composition current minus current variations of 'the said'intermediate frequency onto a primary radiofrequency car'- rier current and radiating the same as a 4f primary carrier Wave, receiving ata distant station the primary carrier Wave, demodu- ,v latinigrr the same to detect out the intermedi- Vate Q mitting theoriginal intermediate frequency carrier currentseparately and by means of a equency Composition current, transseparate `mediumto the receiving station for recomposition with said detected composition current to produce a carrier currentbf the intermediate Yfrequency modulated with the audio signal Wave, and demodulating or detectingthe audio signal Waves therefrom.

2. The method of broadcasting intelligence which comprises modulating,V audio :signal waves onto a carrier current of superaudio intermediate frequency, transmitting ona primary carrier Wave of radio frequency aband of frequencies resulting from said 2 n modulation without the unmodulated portion l 1 ofthe intermediate frequency Waves, trans- 1 kmitting separately and by means of a separate medium to a distant receiving station the ycarrier current of` intermediate frequency, receiving the primary radio fre- 'quencyvvaves at the receiving station, detectii'ig outV the band, combining the band With the intermediate carrier, and detecting the audio frequency signals from the com* l bined currents.- l

VThe method of broadcasting intelligence which comprises transmitting a radio carrier Wave modulated with a band of quency essential to clear'reception, transmitting Waves of said rately and by means to a given point, and bining the separately transmitted Waves with the radio transmitted Waves.

5. In a system of broadcast distribution, a source of current of given intermediate frequency, a source of radio frequency current, means for combining audio gi ven frequency sepaof l a ,separate medium current to produce a band `of yintermediate frequencies substantially Without current variations of the said given intermediate frequency, means for modulating said band. onto said radio frequency current, means for transmitting said modulated radio frequency currents as radio Waves, a receiving station, a radio receiving set at said station for receiving said radio Waves, a Wire line arranged to receive Waves of said given intermediate frequency directly and separately from said sourceqand adapted to convey the same overl the line to thereceiving station, and means at the receiving station for combiningV the frequency sig- L naling current With intermediate frequency at the given point com- Waves kreceived over the Wire line With the y received radio Waves.

6. The system claimed in claim 5 in which the radio frequency current is a harmonic of said given intermediate frequency, with an harmonic producer for the same energized from the source of intermediate frequency.

current,uudin which tlieconnection tothe wire line is made between said source andVr said harmonic producer whereby the intermediate frequency Waves are transmitted directly and separately fromall modulated waves. k

7. The system claimed in claim v5 in which.

the source of radio frequencyA current is a.

harmonic producer supplied with 'fundamental frequency eurrent from saidsource of intermediate frequency current, and the line connection is through an intermediate frequency or longwave amplifier connected in parallel with said harmonic producer.

In testimony whereof I hereunto affix my signature.V f

EDWARD E. CLEMENT. 

